Classifications

• • C—CHEMISTRY; METALLURGY
  • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
  • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
  • C25D5/00—Electroplating characterised by the process; Pretreatment or after-treatment of workpieces
  • C25D5/10—Electroplating with more than one layer of the same or of different metals
  • C25D5/12—Electroplating with more than one layer of the same or of different metals at least one layer being of nickel or chromium
  • C25D5/14—Electroplating with more than one layer of the same or of different metals at least one layer being of nickel or chromium two or more layers being of nickel or chromium, e.g. duplex or triplex layers
• • C—CHEMISTRY; METALLURGY
  • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
  • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
  • C25D5/00—Electroplating characterised by the process; Pretreatment or after-treatment of workpieces
  • C25D5/60—Electroplating characterised by the structure or texture of the layers
  • C25D5/605—Surface topography of the layers, e.g. rough, dendritic or nodular layers
  • C25D5/611—Smooth layers
• • C—CHEMISTRY; METALLURGY
  • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
  • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
  • C25D5/00—Electroplating characterised by the process; Pretreatment or after-treatment of workpieces
  • C25D5/627—Electroplating characterised by the visual appearance of the layers, e.g. colour, brightness or mat appearance

Definitions

• the invention relates to a method for the manufacture of a sanitary fitting with a stainless steel finish.
• Sanitary fittings particularly water supply fittings and sanitary shut-off devices, in general, are often used directly together with stainless steel sinks and have the disadvantage that they clearly differ, in particular, visually and haptically, from the material of the stainless steel sink.
• the object underlying the present invention is to propose sanitary fittings, in particular, water supply fittings and sanitary shut-off devices, in general, which visually and haptically are very similar to or scarcely distinguishable (stainless steel finish) from the stainless steel surface of stainless steel sinks, and a method for their manufacture, wherein starting materials which may be processed more cost-effectively are used.
• the method according to the invention for the manufacture of sanitary fittings with a stainless steel finish may be applied to fittings and parts thereof, which are made from brass, zinc diecasting alloys and plastics. Depending on the starting material, slight modifications are required in the preparation of the fittings or parts thereof for the following common operations for nickel-plating and subsequent chromium-plating.
• the fittings or parts thereof are made from brass, and these are first surface-polished. Subsequently (or alternatively) a pre-brushing is recommended.
• the pre-brushing is recommended particularly for parts with recesses, and, in particular, the recesses should be pre-brushed.
• plastic materials are used.
• plastic materials do not require any such pretreatment, although they may be coated with a layer of copper for better processing in the subsequent nickel-plating process.
• the fittings or parts thereof are made from zinc diecasting alloys.
• the surface When fitting parts or fittings made of zinc diecasting alloys are used, the surface must first be plated with copper in order to close the surface pores present in zinc diecasting alloy parts (particularly ZAMAK alloy parts) and to obtain a sufficiently smooth surface.
• the metal layers of nickel and chromium may be combined so as to obtain a silver-gray, dull gloss, which essentially corresponds to the silver-gray tint of stainless steel.
• a yellow tinge as is known in the case of nickel-plated surfaces, is avoided, and, on the other hand, the blue tinge of a standard chromium-plated surface is also avoided.
• the brushing of the nickel surface should preferably result in a surface structure as is obtained with 3M wheels of the SBI-A type, 250 mm diameter and a working speed of 600 revolutions per minute.
• the fitting parts Prior to the nickel-plating, the fitting parts are preferably degreased in one or preferably several separate operations, and it is further preferred for a chemical degreasing, an ultrasonic degreasing and an electrolytic degreasing operation to follow one another.
• the nickel bath preferably comprises 60 to 80 grams of nickel metal per liter, which is preferably furnished in the form of nickel chloride and nickel sulfate.
• a preferred additive in the electrolytic nickel bath is boric acid, which is preferably added in the amount of 30 to 50 grams per liter, in particular, preferably 40 grams per liter.
• the nickel-plating is preferably carried out with a current density of 4 to 5 amps per square decimeter. Lower current densities are used for nickel-plating brass parts, and higher current densities in the case of previously copper-plated ZAMAK or plastic (particularly ABS) parts.
• the above-mentioned degreasing operations last, as a rule, fractions of minutes or only a few minutes.
• the nickel-plating operation will preferably last 15 to 25 minutes, depending on what average nickel layer thickness is to be produced on the component. With the above-mentioned specifications, an average nickel layer thickness in the range of 18 to 24 ⁇ m is obtained. It has been found that such layer thicknesses are sufficient to withstand a subsequent brushing procedure, as described hereinabove, and to produce an adequate brush structure. Larger layer thicknesses are, of course, possible, for the present invention, but this does not result in any greater advantages in the appearance of the parts. In any case, the layer thickness of the nickel layer must be large enough for a closed nickel surface to remain after the brushing procedure.
• the parts are rinsed, preferably with demineralized water at the end.
• the parts are subsequently dried in a kiln at a temperature of 60 to 75° C.
• the nickel-plating is then followed by a chromium-plating, which may be carried out in the same manner for all parts.
• the parts no longer differ outwardly, i.e., with respect to the electrolytic bath, so that the following recommendations apply to the processing of brass, zinc diecasting alloys and also to plastic parts.
• degreasing operations Prior to the chromium-plating, degreasing operations are also to be performed after the brushing of the nickel-plated surfaces. However, these are to be carried out for all fittings and fitting parts thereof irrespective of what starting material they are made from. Here, too, it is advisable to carry out a number of degreasing operations, which include a chemical, an ultrasonic and an electrochemical degreasing.
• the electrolyte bath for the chromium-plating preferably contains chromium trioxide in an amount of 300 to 350 grams per liter, smaller amounts of sulfuric acid and a common catalyst.
• the chromium-plating process usually lasts 3 to 4 minutes and is carried out at a current strength of preferably 6.5 to 8 amps per square decimeter at a voltage of 3.2 to 5.6 volts. Under these conditions, an average layer thickness in the range of 0.1 to 0.3 ⁇ m is obtained.
• This chromium layer thickness is adequate for many applications. For surfaces exposed to harsh conditions, particularly those which are often cleaned with abrasive cleaning agents or cleaning equipment, significantly thicker chromium layer thicknesses are recommended, but it must be ensured that the brush structure will shine through to a sufficient extent.
• the polished and optionally pre-brushed brass parts are subjected to an ultrasonic degreasing in an aqueous medium at a temperature of 60 to 85° C., preferably approximately 75° C.
• the aqueous medium contains a degreasing agent, selected from tensides, aminically saponified fatty acids, weak organic acids and/or glycol ethers in respectively effective amounts.
• a chemical degreasing is carried out once or several times at temperatures preferably in the range of 40 to 60° C. using an aqueous degreasing medium containing alkali hydroxide as main constituent and, in addition, further constituents selected from alkali metasilicate, sodium carbonate as well as phosphates and tensides. Solutizers, in particular, weak sequestrants may also be present.
• Alkyl benzene sulfonates and ethoxylated fatty alcohols are used as dispersants and/or tensides.
• the amount of degreasing agent in the medium is preferably reduced, for example, halved with each further degreasing operation.
• a cathodic degreasing using an aqueous medium containing alkali hydroxide as main constituent of the degreasing agents is preferably carried out.
• the medium may contain one or several alkali silicates, sodium carbonate, phosphates and tensides.
• a medium is used as described hereinabove for the cathodic degreasing, but preferably with a smaller amount of degreasing agent in the medium.
• a medium is used as described hereinabove for the cathodic degreasing, but preferably with a smaller amount of degreasing agent in the medium.
• half of the degreasing agent in the medium may suffice.
• the anodic and the cathodic degreasing may also be carried out in reverse order, and, in either case, it applies for the respective second electrolytic degreasing operation that the smaller amount of degreasing agent will preferably be used here in the medium.
• rinsing, neutralizing and rinsing again are carried out prior to the nickel-plating, with sulfuric acid preferably being used for the neutralizing.
• the rinsing procedures are carried out once or several times.
• nickel content in the electrolyte preferably 60 to 80 grams nickel content per liter.
• the nickel content is made from nickel salts which are preferably nickel chloride hexahydrate and nickel sulfate hexahydrate. It is particularly preferred for these two salts to be used alongside each other, with a ratio of approximately 1:4 being particularly preferred. Boric acid with a content of 30 to 40 grams per liter is used as further constituent of the electrolyte for the nickel-plating.
• the length of time of the nickel-plating process does, of course, depend largely on the layer thickness aimed at. Usually, 15 to 25 minutes at a voltage of 6.2 to 8.3 volts and a current density of approximately 4 amps per square decimeter will be sufficient for the nickel-plating.
• the thus formed nickel layer has an average layer thickness in the range of 18 to 24 ⁇ m. This layer thickness is thick enough for a brush structure to be able to be imparted to the surface.
• the brush structure should correspond to a brush structure such as obtained with grinding wheels of the company 3M of the SBI-A type having a diameter of 250 mm, when these grinding wheels are driven at a working speed of 600 revolutions per minute.
• the ZAMAK parts (generally zinc diecasting alloy parts) are first provided with a copper layer in order to smooth the surface, i.e., in order to close surface pores resulting from the diecasting and ensure a smooth surface. After this, the copper-plated ZAMAK parts can be treated like the ABS parts, whether these are copper-plated or not.
• a chemical degreasing is first carried out in an aqueous medium with a degreasing agent which is predominantly formed by alkali hydroxide, but, in addition, contains larger amounts of sodium carbonate, alkali metasilicates and alkylphenol ethoxylates. Tensides in a smaller amount may also be present.
• a degreasing agent which is predominantly formed by alkali hydroxide, but, in addition, contains larger amounts of sodium carbonate, alkali metasilicates and alkylphenol ethoxylates. Tensides in a smaller amount may also be present.
• an ultrasonic degreasing is carried out, with a degreasing agent formed predominantly by sodium borate and sodium carbonate being added to the aqueous degreasing medium.
• a degreasing agent formed predominantly by sodium borate and sodium carbonate is added to the aqueous degreasing medium.
• a mixture of various tensides is used.
• the medium essentially contains sodium carbonate and sodium metasilicates and smaller amounts of sodium hydroxide as degreasing agent.
• nickel-plating Prior to the actual nickel-plating, neutralizing is carried out again. Here sulfuric acid is preferably used and rinsing is carried out again with water. The nickel-plating process is then carried out, as described hereinabove, but a somewhat higher current density is preferably used for the ZAMAK parts and ABS parts.
• nickel layer thicknesses in the range of 18 to 24 ⁇ m are obtained in a period of time of 15 to 25 minutes.
• a chemical degreasing is first carried out.
• an aqueous degreasing medium containing degreasing agents predominately formed by sodium hydroxide is used.
• sodium carbonate small amounts of sodium metasilicate and alkylphenol ethoxylates and tensides are additionally contained therein.
• An ultrasonic degreasing is then carried out in an aqueous degreasing medium with a degreasing agent formed predominantly from sodium borate and smaller amounts of sodium carbonate and various tensides.
• the chromium-plating is carried out with a chromium content of 300 to 350 grams per liter of chromium trioxide, small amounts of sulfuric acid and a catalyst comprised of fluorsilicates and sodium chromate.
• the chromium-plating is carried out for 3 to 4 minutes at a current strength of 6.5 to 8 amps per square decimeter and at a voltage of 3.2 to 5.6 volts.
• average chromium layer thicknesses of 0.1 to 0.3 ⁇ m are obtained.
• Rinsing with water is then carried out, at the end with ultrapure water, and, subsequently, drying in the kiln.
• fitting parts have a surface appearance and a surface feel which are scarcely distinguishable from the stainless steel finish of real brushed stainless steel surfaces.
• the individual method stages will be set forth hereinbelow in the form of a table. It will be understood that, in particular, the degreasing operations may be performed in a wide variety of different ways, and merely serve to create the preconditions for nickel and chromium layers with good adherence.
• the nickel-plating and chromium-plating processes themselves also allow many variations, the main thing being that the above-described results must be attained for the layer thicknesses.
• ZAMAK zinc diecasting alloy parts refers to parts made from zinc alloys that contain aluminum, magnesium, and copper and that are available in the United States from Eastern Alloys, Inc., Maybrook, N.Y.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Electrochemistry (AREA)
• Materials Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Electroplating Methods And Accessories (AREA)
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• 2003
  • 2003-03-19 DE DE10312308A patent/DE10312308A1/de not_active Withdrawn
• 2004
  • 2004-03-17 EP EP04721193A patent/EP1611269A1/de not_active Withdrawn
  • 2004-03-17 CA CA2526077A patent/CA2526077C/en not_active Expired - Fee Related
  • 2004-03-17 WO PCT/EP2004/002812 patent/WO2004083491A1/de active Application Filing
• 2005
  • 2005-09-12 US US11/224,636 patent/US7854831B2/en not_active Expired - Fee Related

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